On Sat, Sep 06, 2003 at 12:38:48AM -0700, Paul Johnson wrote: > On Fri, Sep 05, 2003 at 04:53:53PM +0100, Pigeon wrote: > > Well, it does sound like they have much bigger engines than what they > > replace. > > Not really, they sound like they're the identical engine. The > difference is hydraulic and manual transmissions waste serious, > serious amounts of energy. The worst ancient American slushboxes had efficiencies around 50%; modern ones are a lot better, I think around 75%. Electric transmission in a locomotive is around 85%, but smaller installations will be less efficient. The performance increase you describe sounds like it's due to rather more than the relatively small percentage increase you'd get from a different transmission type. Manual transmissions are more efficient than either, so a manual car uses less fuel than an automatic on a run; but in town, they suffer from the fixed ratios meaning that the engine spends a lot of its time not in the most fuel-efficient rev range, so even old inefficient automatics have long been able to give better fuel consumption than a manual in urban driving (at least with small-engined European cars; don't know how American V8 gas guzzlers compare). A good compromise seems to be torque-converter lockup systems that bypass the torque convertor in top gear. > Gasoline (oppose diesel) is also a pretty > poor choice for fuel. Which is why I have to wonder: It's 2003, and > we're *still* using gasoline-mechanical and gasoline-hydraulic systems > for what reason? Tradition and vested interests. Why are we still using telescopic forks for motorcycle front ends? Why is there Microsoft software? > Lets move *on*, people! We can make traffic a mere > nuisance instead of an acute respiratory health hazard (not to mention > the US a military threat to anybody producing oil) if we just > eliminate gasoline in favor of cleaner burning diesel and/or electric > transmissions. Don't quite follow you here. Diesel engines are more efficient, sure, but not that much. Then there are all the industrial uses of oil, which are mostly not gasoline-based already. To stop oil being a political problem, using a different fraction to power cars isn't enough; you've got to stop using oil as a fuel altogether. As for the pollution aspect, diesels are again cleaner but not hugely so. Any hydrocarbon fuel is going to give you carbon monoxide and unburnt hydrocarbons, as well as lots of carbon dioxide however clean-running your engine is in other respects. And any fuel burned in air will produce nitrogen oxides. The thing is to eliminate the need for combustion entirely. Fuel cells running on biologically produced methanol are one possibility, if you can grow enough vegetation without ruining the land. > > In the UK, an electrically powered bicycle counts as a bicycle, not a > > moped (ie. no road tax, no insurance, no helmet etc) as long as it has > > (a) powered top speed <=15mph (b) max power <=200W (c) max weight > > <=40kg. 15mph is OK for a bicycle, but 40kg means you get really crap > > range with a lead-acid battery; a fuel cell sounds great, as long as > > it runs on methanol or some other convenient fuel rather than hydrogen. > > Oh, the last thing I want to be running on is liquid fuel in general. > Liquid fuels have this fun tendancy of splashing about and catching > fire in accidents, incinerating victims slowly. I think we do remarkably well in avoiding this sort of problem. Of course, things are different with that explosive steel they make American cars out of, but the hero always gets out just before it explodes, and the villains would be dead whatever happened. :-) > Hydrogen is far, far > safer: If a fuel leak ignites, *whump*, done. No more burning. It > just flashes and it's over. Yeah, you'll get toasted and you'll > probably end up hospitalized, but it beats dying like a monk without a > cause. The storage devices have a tendency to turn into bombs or missiles, according to type of device and/or accident. I don't really know which would end up being safer overall, but as well as the storage difficulties, hydrogen has problems in terms of where do you get it from. > > The biggest problem is that the max power of 200W is totally useless > > in hilly areas. To get a 40kg bike + rider + luggage up a 1 in 4 gradient > > fast enough to maintain balance requires about a horsepower. > > Any skilled rider should be good down to 1MPH. I can go slower than that, waiting for cars to clear a junction so I don't have to actually stop; but it's not something I'd care to do for long distances with cars overtaking me all the time. Without the cars it wouldn't be so bad. > Of course, going that > slow, why not just walk? It would be 3 to 5 times faster. 8:o) Shoving the bike up the hill, then I'd be producing the 1hp myself... OK if you're a physical fitness freak, but I like my bike for the convenience, ease and cheapness. -- Pigeon Be kind to pigeons Get my GPG key here: http://pgp.mit.edu:11371/pks/lookup?op=get&search=0x21C61F7F
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